Electric heating device and process of constructing the same.



w. s HADAWAY, JR.

ELECTRIC, HEATING DEVICE AND PROCESS OF OONSTRUCTING THE SAME.

APPLICATION FILED FEB.25,1909.

Patented Oct. 29, 1912.

WITNESSES:

INVENTOR Maw? UNITED STATES PATENT OFFICE.

WILLIAM S. HADAWAY, JR.,- OF EAST ORANGE, NEW JERSEY, .ASSIGNOR T0 WESTINGHOUSE ELECTRIC AND.MANUFACTURING CQMPANY, A CORPORA- TION OF PENNSYLVANIA.

Specification of Letters Patent.

Patented Oct. 29,1912.

Application filed February 25, 1909. Serial No. 479,978.

To all whom it may concern;

Be it known thatI, WILLIAM S. HADAWAY, Jr, a citizen of the United States, and a resident of East Orange, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in Electric Heating Devices and Processes of Constructing the Same, of which the following is a specification.

My invention relates to electric heating and resistance devices and it has special reference to such devices as are inclosed in casings of heat-conducting material and are adapted to be immersed in water or other liquid.

One object of my invention is to provide a device of the class above indicated that shall be durable in construction and effective in operation.

A second object of my invention is to provide a simple process by which a device of the class just referred to may be advantageousl constructed.

In or er that electric heaters may be eeonomically operated, either when they are immersed in water or other liquid, or when they are operated in the air, it is desirable to provide a water-tight casin for the resistance element which shall e relatively rigid and durable and a good conductor of heat. Metal casings are usually employed for this purpose, but it has been found difficult to avoid air spaces between the metal covering and the insulation which necessarily surrounds the resistance element within the covering.

According to my present invention, I provide a heating device in which the metal inclosing casing is held in very close engagement with the insulation surrounding the resistance element, the arrangement of parts being such that the heat generated within the casin is ra idly conducted to its outer surface, rom W ich it is dissipated into the surrounding medium.

My invention is illustrated in the accompanying drawings, in WlllCl1- Figure 1 is a sectional view of the resistance element and the insulation as they appear before the parts are assembled. Fig. 2 is a similar view of the resistance element after'it has been embedded in the insulation, as hereinafter pointed out. Fig. 3 is a perspective view of a portion of t is resistance element with a covering of sheet metal or metal foil partially applied, to it.

steps which may be employed in practising my improved process, and Fig. 5 is a sec? tional elevation of the completed heating device. l r I Referring to the drawings, a resistance element 1 in the form of a conducting ribbon which is providedwith a luralityof slots to produce a zig-zag path or the electric current, is illustrated, but, while this form is considered preferable, it may be re: placed by any suitable resistance element within the scope of my invention.

The resistance ribbon is first assembled between similar strips 2 of insulating mate rial, the construction of which is such that they are fused together upon the application of heat, forming a substantially homogeneous body of insulation, in which the resistance element is embedded (See Fig. 3). The insulated ribbon is then inclosed in a suitable metal casing 8 which is either pressed or brought by other means into close engagement with it. The resistance terminals may be located at the same end or at opposite ends of the unit, as may be desired, both arrangements being well known in the art. It the form of the completed heater is relatively simple, the casing may be applied, as hereinafter pointed out, after the resistance element has been formed into the desired shape. It will usually be found preferable, however, to bend the heater into its final form after the resistance element has been assembled in the casing and the device is otherwise complete. Considerable advantage is gained by compressing the metal casing in ordertobring the insulation and the resistance element under pressure and thereby to exclude air and improve the thefinal-conductivity of the device.

he successfully formed on the insulated re sistance element comprises the following steps: First, the insulated resistance ribbon iswrappcd with copper foil or with a thin covering of heat-conducting material. A

electrolytically, or otherwise.

Referring to Fig. at of the drawings, the resistance or heater unit 3 is immersed in I Fig. at is v a diagrammatic view illustrating one of the One method by which the coating may v deposit of copper or other suitable material is then produced upon the metal covering" a suitable liquid, its covering of sheet metal forming one electrode of an electroplating cell 4. Energy is supplied from any suitable source, such 'as generator 5, through conductor 6, toLan electrode 7. circuit being completed from this point through the metal casing 8 on the surface of the resistance unit and conductor 9 to the opposite terminal of the generator. The electroplating process is continued until a relatively thick coating of metal 10 is deposited on the resistance unit. In this way, a Water-tight heat-con ducting sheath or covering is provided which is in close contact with the insulating sheath 2 and is sufiiciently strong to Withstand the Wear and tear of ordinary use.

It will be readily understood by those skilled in the art that the heater unit should be kept in a relatively simple form until after the electroplating process is completed in order that the Walls of the deposited coating may be more nearly uniform.

\Vhile it is considered preferable to use copper foil or some similar material for first covering the insulating sheath, this material may be replaced by an application of graphite or other conducting material on which a suitable deposit of heatconducting material may be electrolytically produced.

It Will, of course be understood that structural modifications may be effected in the device, and that various methods may be utilized for producing it.

I claim as my invention:

1. The process of constructing an electric resistance or heater which consists in coating an insulated resistance element with conducting material and electrolytically producing a deposit of heat-conducting material thereon.

2. The process of constructing an electric resistance or heater which consists in embedding a resistance ribbon in an insulating sheath, covering the insulation with metal foil and electrolytically producing a deposit of heat-conducting material on the outer surface of the covering.

In testimony whereof, I have hereunto subscribed my name this 20th day of F eb., 1909.

i/VILLIAM S. HADAWAY. JR.

Witnesses W. B. UNDERWOOD, B. B. HINES. 

